Recently, it has been considered to form a transistor array including a plurality of organic thin-film transistors (organic TFT) on a plastic board by a low-cost process and apply the transistor array to a backplane for an electronic paper, a liquid crystal display and the like. In a manufacturing method of the organic thin-film transistors, in order to differentiate the thin-film transistors from a typical silicon TFT, it is strongly desired that configuration components are formed in a pattern at a low cost only by a printing process without performing a vacuum process and a photolithography technique.
In such a background, a method of forming by printing a VIA for electrically connecting conductors such as the transistor array and the wiring pattern has been considered. For instance, a method has been proposed including: forming an insulative film on a board in a manner to cover a wiring pattern provided on the board; repeating ejecting a solvent for dissolving the insulative film toward the insulative film on the wiring pattern by inkjet printing and drying the solvent, thereby forming a VIA hole reaching the wiring pattern; and filling the VIA hole with an conductive material (see, for instance, Patent Literature 1). Moreover, a method of forming a VIA in an especial shape by inkjet printing directly on a wiring pattern provided on a board has been proposed (see, for instance, Patent Literature 2).